This invention relates to apparatus for and a process of die casting a metal part in which a particulate inert filler material is intermixed with the molten metal thereby to form a casting having the inert filler material substantially uniformly distributed throughout the casting so as to reduce the amount of metal required to make the casting.
In the die casting of many parts, for example, in the die casting of end shields for electric motors or the like, certain portions of the casting are required to be of a minimum thickness solely to facilitate die casting of the part. Oftentimes, this minimum thickness is greater than is required for purposes of strength. Thus, many die castings are excessively costly and result in the "wasting" of expensive materials in that these materials are not efficiently used. Through trial and error experience, it has been found that in order to produce a satisfactory die casting, a minimum thicknesses of various sections of the casting must be maintained in order to result in satisfactory castings.
Reference may be made to U.S. Pat. Nos. 2,793,949, 3,147,087 and 3,239,319 which relate broadly to the same general field as the process and apparatus of the present invention. Specifically, U.S. Pat. No. 2,793,949 discloses utilizing a wetting agent to overcome the surface tension of molten metal thereby to permit mixing of the molten metal with particles of an inorganic, non-metallic material. U.S. Pat. No. 3,147,087 discloses the provision of an abradable material consisting of graphite or graphite and mica particles disposed in an aluminum matrix in the proportion of about 2.5-10% by weight. U.S. Pat. No. 3,239,319 discloses a process of filling a mold cavity with a particulate, non-metallic, inorganic material, and applying a vacuum to the mold cavity so as to draw molten metal into the cavity and to completely fill the voids between the particles.
Among the several objects and features of the present invention may be noted the provision of apparatus for and a process of die casting metal parts in which the amount of metal required for the die casting is substantially reduced (e.g., up to sixty percent of the amount of metal used in the casting may be saved) and yet which results in a casting of adequate strength and satisfactory appearance;
the provision of such a die casting process and apparatus which utilizes an inert particulate filler material which is uniformly mixed with the die cast metal so as to form a die cast part having the inert filler materials substantially uniformly distributed throughout the part; PA1 the provision of such a die casting process and apparatus which may be utilized without substantial modifications to conventional die casting manufacturing processes and equipment; PA1 the provision of such a die casting process and apparatus which may be cycled at acceptable production rates; PA1 the provision of such a process and method which, in one embodiment thereof, may be used to die cast the part without the premixing of the inert particulate filler material and the molten metal; PA1 the provision of such a die casting process and apparatus which, in another embodiment thereof, utilizes a premixed inert particulate filler material and molten metal to die cast a part with the particulate filler material substantially uniformly distributed throughout the die cast part; PA1 the provision of such a die casting process and apparatus which when used to fabricate a die cast end shield of an electric motor, results in reduced noise of the motor because the resulting die cast end shield has less of a tendency to transmit sound therethrough; and PA1 the provision of such a process and apparatus which results in reduced material costs, and yet which maintains or may even improve the strength of the part.
Other objects and features of this invention will be in part apparent and in part pointed out hereinafter.